Petrophysical and rock physics analysis of Pindori-01 well, eastern potwar plateau, upper Indus basin, Pakistan (P-0914) (MFN 3649)

Abstract

The present study is undertaken to evaluate the hydrocarbon potential of Pindori- 01, Upper Indus Basin, Pakistan. This has been achieved with the help of wire line logs and available well data. During study, all logs are correlated to mark the zone of interest i.e. reservoir zone. The shale volume are evaluated by gamma ray log, porosities of the reservoir zone by density and neutron log, resistivity of water by using resistivity log and saturation of water in the zone of reservoir & hydrocarbon saturation with the help of Archie’s equation. In present study the reservoir lies in Chorgali Formation and Sakesar Formation of Eocene age. After the demarcation of reservoir zone of about 190 feet, this zone was then divided into three sub zones: Zone 1 (Chorgali Formation) is 40 feet thick and thickness of Zone 2 (Sakesar Formation) is 76 feet. The reservoir zone formations are mainly comprised of limestone which has average shale volume estimated for zone 1 Chorgali Formation is 18.32% and 14.96% for zone 2 Sakesar Formation. Average Porosity estimated for zone 1 Chorgali Formation is 16.90% and 19.80% of zone 2 Sakesar Formation. Average water saturation estimated for zone 1 Chorgali Formation is 62.06% while 65.73% of zone 2 Sakesar Formation. Average hydrocarbon saturation estimated for zone 1 Chorgali Formation is 37.93% while 34.26% for zone 2 Sakesar Formation. Rock physics primarily uses sonic log and with the help of P-wave velocity (Vp), S-wave velocity (Vs), density, and their relationships to elastic moduli κ (bulk modulus) and μ (shear Modulus), E (young modulus) porosity, for given lithology and fluid types are analyzed. The relationships between the elastic parameters i.e. Vp, Vs, bulk modulus, shear modulus, young modulus and poison ratio were analyzed which reflected that changes in formations occurred due to overburden, porosity and the presence of fluids in the porosities. Since the porosity in evaporites is very low therefore we can infer that there is no primary porosity in limestone. The petrophysical analysis and rock mechanics of Pindori-01 led to the identification of characteristics which help in marking of the hydrocarbon horizons.